An anonymous survey of nearly 2,000 retired officers found that the manipulation of crime reports — downgrading crimes to lesser offenses and discouraging victims from filing complaints to make crime statistics look better — has long been part of the culture of the New York Police Department.

The story also quotes Frank Zimring, whose separate research "compared the department’s crime data for homicide, robbery, auto theft and burglary to insurance claims, health statistics and victim surveys and found a near-exact correlation."

He said that there was always “some underreporting, and there is some downgrading in every police force that I know of,” but that his research showed that any manipulation was too minuscule to significantly affect the department’s crime statistics.